﻿using System;
using System.Net;
using System.IO;
using System.Text;
using System.Net.Sockets;

namespace FtpLib
{

    public class FTPFactory
    {

        public string remoteHost = "localhost";
        public string remotePath = ".";
        public string remoteUser = "anonymous";
        public string remotePass = "anon@anon.com";
        public int remotePort = 21;

        private string mes;
        private int bytes;
        private Socket clientSocket;

        private int retValue;
        private Boolean debug;
        private Boolean logined;
        private string reply;

        private static int BLOCK_SIZE = 512;

        Byte[] buffer = new Byte[BLOCK_SIZE];
        Encoding ASCII = Encoding.ASCII;

        public FTPFactory()
        {
            debug = false;
            logined = false;

        }
        
        ///
        /// Return a string array containing the remote directory's file list.
        ///
        ///
        ///
        public string[] getFileList(string mask)
        {
            if(!logined)
            {
                login();
            }

            Socket cSocket = createDataSocket();

            sendCommand("NLST " + mask);

            if(!(retValue == 150 || retValue == 125))
            {
                throw new IOException(reply.Substring(4));
            }

            mes = "";

            while(true)
            {

                int bytes = cSocket.Receive(buffer, buffer.Length, 0);
                mes += ASCII.GetString(buffer, 0, bytes);

                if(bytes < buffer.Length)
                {
                    break;
                }
            }

            char[] seperator = {'\n'};
            string[] mess = mes.Split(seperator);

            cSocket.Close();

            readReply();

            if(retValue != 226)
            {
                throw new IOException(reply.Substring(4));
            }
            return mess;

        }

        ///
        /// Return the size of a file.
        ///
        ///
        ///
        public long getFileSize(string fileName)
        {

            if(!logined)
            {
                login();
            }

            sendCommand("SIZE " + fileName);
            long size=0;

            if(retValue == 213)
            {
                size = Int64.Parse(reply.Substring(4));
            }
            else
            {
                throw new IOException(reply.Substring(4));
            }

            return size;

        }

        ///
        /// Login to the remote server.
        ///
        public void login()
        {

            clientSocket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
            IPEndPoint ep = new IPEndPoint(Dns.GetHostEntry(remoteHost).AddressList[0], remotePort);
            
            try
            {
            clientSocket.Connect(ep);
            }
            catch(Exception)
            {
            throw new IOException("Couldn't connect to remote server");
            }

            readReply();
            if(retValue != 220)
            {
                close();
                throw new IOException(reply.Substring(4));
            }
            if(debug)
                Console.WriteLine("USER "+remoteUser);

            sendCommand("USER "+remoteUser);

            if( !(retValue == 331 || retValue == 230) )
            {
                cleanup();
                throw new IOException(reply.Substring(4));
            }

            if( retValue != 230 )
            {
                if(debug)
                    Console.WriteLine("PASS xxx");

                sendCommand("PASS "+remotePass);
                if( !(retValue == 230 || retValue == 202) )
                {
                    cleanup();
                    throw new IOException(reply.Substring(4));
                }
            }

            logined = true;
            Console.WriteLine("Connected to "+remoteHost);

            chdir(remotePath);

        }

        ///
        /// If the value of mode is true, set binary mode for downloads.
        /// Else, set Ascii mode.
        ///
        ///
        public void setBinaryMode(Boolean mode)
        {

            if(mode)
            {
                sendCommand("TYPE I");
            }
            else
            {
                sendCommand("TYPE A");
            }
            if (retValue != 200)
            {
                throw new IOException(reply.Substring(4));
            }
        }

        ///
        /// Download a file to the Assembly's local directory,
        /// keeping the same file name.
        ///
        ///
        public void download(string remFileName)
        {
            download(remFileName,"",false);
        }

        ///
        /// Download a remote file to the Assembly's local directory,
        /// keeping the same file name, and set the resume flag.
        ///
        ///
        ///
        public void download(string remFileName,Boolean resume)
        {
            download(remFileName,"",resume);
        }

        ///
        /// Download a remote file to a local file name which can include
        /// a path. The local file name will be created or overwritten,
        /// but the path must exist.
        ///
        ///
        ///
        public void download(string remFileName,string locFileName)
        {
            download(remFileName,locFileName,false);
        }

        ///
        /// Download a remote file to a local file name which can include
        /// a path, and set the resume flag. The local file name will be
        /// created or overwritten, but the path must exist.
        ///
        ///
        ///
        ///
        public void download(string remFileName,string locFileName,Boolean resume)
        {
            if(!logined)
            {
                login();
            }

            setBinaryMode(true);

            Console.WriteLine("Downloading file "+remFileName+" from " + remoteHost + "/" + remotePath);

            if (locFileName.Equals(""))
            {
                locFileName = remFileName;
            }

            if(!File.Exists(locFileName))
            {
                Stream st = File.Create(locFileName);
                st.Close();
            }

            FileStream output = new
            FileStream(locFileName,FileMode.Open);

            Socket cSocket = createDataSocket();

            long offset = 0;

            if(resume)
            {

                offset = output.Length;

                if(offset > 0 )
                {
                    sendCommand("REST "+offset);
                    if(retValue != 350)
                    {
                    //throw new IOException(reply.Substring(4));
                    //Some servers may not support resuming.
                        offset = 0;
                    }
                }

                if(offset > 0)
                {
                    if(debug)
                    {
                        Console.WriteLine("seeking to " + offset);
                    }
                    long npos = output.Seek(offset,SeekOrigin.Begin);
                    Console.WriteLine("new pos="+npos);
                }
            }

            sendCommand("RETR " + remFileName);

            if(!(retValue == 150 || retValue == 125))
            {
                throw new IOException(reply.Substring(4));
            }

            while(true)
            {

                bytes = cSocket.Receive(buffer, buffer.Length, 0);
                output.Write(buffer,0,bytes);

                if(bytes <= 0)
                {
                    break;
                }
            }

            output.Close();
            if (cSocket.Connected)
            {
                cSocket.Close();
            }

            Console.WriteLine("");

            readReply();

            if( !(retValue == 226 || retValue == 250) )
            {
                throw new IOException(reply.Substring(4));
            }

        }

        ///
        /// Upload a file.
        ///
        ///
        public void upload(string fileName)
        {
            upload(fileName,false);
        }

        ///
        /// Upload a file and set the resume flag.
        ///
        ///
        ///
        public void upload(string fileName,Boolean resume)
        {

            if(!logined)
            {
                login();
            }

            Socket cSocket = createDataSocket();
            long offset=0;

            if(resume)
            {

                try
                {

                    setBinaryMode(true);
                    offset = getFileSize(fileName);

                }
                catch(Exception)
                {
                    offset = 0;
                }
            }

            if(offset > 0 )
            {
                sendCommand("REST " + offset);
                if(retValue != 350)
                {
                //throw new IOException(reply.Substring(4));
                //Remote server may not support resuming.
                    offset = 0;
                }
            }

            sendCommand("STOR "+Path.GetFileName(fileName));

            if( !(retValue == 125 || retValue == 150) )
            {
                throw new IOException(reply.Substring(4));
            }

            // open input stream to read source file
            FileStream input = new
            FileStream(fileName,FileMode.Open);

            if(offset != 0)
            {

                if(debug)
                {
                    Console.WriteLine("seeking to " + offset);
                }
                    input.Seek(offset,SeekOrigin.Begin);
            }

            Console.WriteLine("Uploading file "+fileName+" to " + remotePath);

            while ((bytes = input.Read(buffer,0,buffer.Length)) > 0)
            {

                cSocket.Send(buffer, bytes, 0);

            }
            input.Close();

            Console.WriteLine("");

            if (cSocket.Connected)
            {
                cSocket.Close();
            }

            readReply();
            if( !(retValue == 226 || retValue == 250) )
            {
                throw new IOException(reply.Substring(4));
            }
        }

        ///
        /// Delete a file from the remote FTP server.
        ///
        ///
        public void deleteRemoteFile(string fileName)
        {

            if(!logined)
            {
                login();
            }

            sendCommand("DELE "+fileName);

            if(retValue != 250)
            {
                throw new IOException(reply.Substring(4));
            }

        }

        ///
        /// Rename a file on the remote FTP server.
        ///
        ///
        ///
        public void renameRemoteFile(string oldFileName,string newFileName)
        {

            if(!logined)
            {
                login();
            }

            sendCommand("RNFR "+oldFileName);

            if(retValue != 350)
            {
                throw new IOException(reply.Substring(4));
            }

            // known problem
            // rnto will not take care of existing file.
            // i.e. It will overwrite if newFileName exist
            sendCommand("RNTO "+newFileName);
            if(retValue != 250)
            {
                throw new IOException(reply.Substring(4));
            }

        }

        ///
        /// Create a directory on the remote FTP server.
        ///
        ///
        public void mkdir(string dirName)
        {

            if(!logined)
            {
                login();
            }

            sendCommand("MKD "+dirName);

            if(retValue != 250)
            {
                throw new IOException(reply.Substring(4));
            }

        }

        ///
        /// Delete a directory on the remote FTP server.
        ///
        ///
        public void rmdir(string dirName)
        {

            if(!logined)
            {
                login();
            }

            sendCommand("RMD "+dirName);

            if(retValue != 250)
            {
                throw new IOException(reply.Substring(4));
            }

        }

        ///
        /// Change the current working directory on the remote FTP server.
        ///
        ///
        public void chdir(string dirName)
        {

            if(dirName.Equals("."))
            {
                return;
            }

            if(!logined)
            {
                login();
            }

            sendCommand("CWD "+dirName);

            if(retValue != 250)
            {
                throw new IOException(reply.Substring(4));
            }

            this.remotePath = dirName;

            Console.WriteLine("Current directory is "+remotePath);

        }

        ///
        /// Close the FTP connection.
        ///
        public void close()
        {

            if( clientSocket != null )
            {
                sendCommand("QUIT");
            }

            cleanup();
            Console.WriteLine("Closing…");
        }

        ///
        /// Set debug mode.
        ///
        ///
        public void setDebug(Boolean debug)
        {
            this.debug = debug;
        }

        private void readReply()
        {
            mes = "";
            reply = readLine();
            retValue = Int32.Parse(reply.Substring(0,3));
        }

        private void cleanup()
        {
            if(clientSocket!=null)
            {
                clientSocket.Close();
                clientSocket = null;
            }
            logined = false;
        }

        private string readLine()
        {

            while(true)
            {
                bytes = clientSocket.Receive(buffer, buffer.Length, 0);
                mes += ASCII.GetString(buffer, 0, bytes);
                if(bytes < buffer.Length)
                {
                    break;
                }
            }

            char[] seperator = {'\n'};
            string[] mess = mes.Split(seperator);

            if(mes.Length > 2)
            {
                mes = mess[mess.Length-2];
            }
            else
            {
                mes = mess[0];
            }

            if(!mes.Substring(3,1).Equals(" "))
            {
                return readLine();
            }

            if(debug)
            {
                for(int k=0;k < mess.Length-1;k++)
                {
                    Console.WriteLine(mess[k]);
                }
            }
            return mes;
        }

        private void sendCommand(String command)
        {

            Byte[] cmdBytes =
            Encoding.ASCII.GetBytes((command+"\r\n").ToCharArray());
            clientSocket.Send(cmdBytes, cmdBytes.Length, 0);
            readReply();
        }

        private Socket createDataSocket()
        {

            sendCommand("PASV");

            if(retValue != 227)
            {
                throw new IOException(reply.Substring(4));
            }

            int index1 = reply.IndexOf('(');
            int index2 = reply.IndexOf(')');
            string ipData = reply.Substring(index1 + 1,index2 - index1 - 1);
            int[] parts = new int[6];

            int len = ipData.Length;
            int partCount = 0;
            string buf="";

            for (int i = 0; i < len && partCount <= 6; i++)
            {

                char ch = Char.Parse(ipData.Substring(i,1));
                if (Char.IsDigit(ch))
                    buf+=ch;
                else if (ch != ',')
                {
                throw new IOException("Malformed PASV reply: " + reply);
            }

            if (ch == ',' || i+1 == len)
            {

                try
                {
                    parts[partCount++] = Int32.Parse(buf);
                    buf="";
                }
                catch (Exception)
                {
                    throw new IOException("Malformed PASV reply: " + reply);
                }
                }
            }

            string ipAddress = parts[0] + "."+ parts[1]+ "." +
            parts[2] + "." + parts[3];

            int port = (parts[4] << 8) + parts[5];

            Socket s = new
            Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
            IPEndPoint ep = new
            IPEndPoint(Dns.GetHostEntry(ipAddress).AddressList[0], port);

            try
            {
                s.Connect(ep);
            }
            catch(Exception)
            {
                throw new IOException("Can't connect to remote server");
            }

            return s;
        }

    }
}
